This post is a compilation of disability statistics from government agencies and researchers in the US, UK and Canada. The statistics shown have most impact on website use, and help assess the impact of accessibility problems, in terms of numbers of people affected, and likely commercial impact.

Incidence of Key Disabilities

Reading Difficulties

15%-20% of people in the US have reading difficulties, including dyslexia (source: nih.gov).

Incidence increases with age, with more than 10% of over-70s affected.

Note: Government statistical agencies produce these numbers from questionnaires, but questions aren't standardized between countries, so figures are not directly comparable from country to country. For example, the questions "do you have difficulty seeing" and "do you have difficulty seeing newsprint" produce different response rates.

Incidence of Disability by Age

Hearing and sight becomes poorer as people get older, but these same people often have large amounts of disposable income and leisure time. This presents particular challenges for web sites selling items which appeal to an older demographic, such as travel and cruises (source: census.gov).